Clean Architecture with .NET Core: A Practical Overview

Clean Architecture is a software design pattern that emphasizes separation of concerns, testability, and maintainability. When applied correctly, it results in systems that are easier to understand, extend, and test.

In the .NET Core ecosystem, Clean Architecture is especially powerful thanks to its support for dependency injection, layered structure, and modular design capabilities.

What Is Clean Architecture?

Proposed by Robert C. Martin (Uncle Bob), Clean Architecture separates an application into distinct layers:

• Domain Layer: Contains core business logic and entities. It is completely independent of any frameworks or external libraries.

• Application Layer: Handles use cases, interfaces, and application-specific logic. It calls the domain layer and orchestrates workflows.

• Infrastructure Layer: Deals with implementation details like data access, third-party services, and APIs.

• Presentation Layer: Represents the UI or API layer, such as controllers in an ASP.NET Core Web API.

Each layer depends only on the one directly beneath it, and the core domain has no dependencies on outer layers.

Benefits of Clean Architecture in .NET Core

1. Testability
   By isolating business logic from external dependencies, you can write unit tests easily without touching the database or UI.

2. Maintainability
   With a clear structure, it’s easier to understand and modify specific parts of the application without breaking others.

3. Flexibility
   You can swap infrastructure implementations (e.g., change from SQL Server to MongoDB) without affecting business logic.

4. Separation of Concerns
   Each layer has a single responsibility, reducing coupling and increasing cohesion.

Folder Structure Example

 /src
     /MyApp.API (Presentation)
     /MyApp.Application (Use Cases)
     /MyApp.Domain (Entities, Interfaces)
     /MyApp.Infrastructure (EF Core, Services)

Each project references only what it needs. For instance, the Application project can reference Domain, but not Infrastructure.

How to Get Started

1. Create a new solution with multiple projects in Visual Studio or CLI

2. Define interfaces in the Domain layer

3. Implement use cases in the Application layer

4. Add infrastructure implementations (like EF Core Repositories) in the Infrastructure layer

5. Use Dependency Injection to inject implementations into the API (Startup.cs / Program.cs)

There are popular templates and starter kits you can explore, like the Jason Taylor Clean Architecture Template.

Final Thoughts

Clean Architecture in .NET Core is more than just organizing folders. It’s about enforcing a scalable and sustainable architecture that makes long-term development easier.

Whether you’re building a small API or a large enterprise solution, following the principles of Clean Architecture helps keep your code clean, focused, and future-proof.